textproduct: Quad Cities

KEY MESSAGES

- Heat, fairly typical for July, will persist into Saturday with highs in the lower to mid 90s and heat indices mainly in the mid 90s to 100 degrees. The heat index in some locations may exceed 100 degrees, but not currently anticipating this to be widespread with probabilities at 20-40% for heat index readings over 100F.

- Canadian wildfire smoke may potentially impact parts of the region late week and into the weekend, as the heat dome breaks down and NW flow develops aloft.

- The break down of the heat dome will lead to an increasing signal for precipitation chances late week and beyond into next week with a return to more seasonable temperatures.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 253 AM CDT Tue Jul 14 2026

Ideal radiational cooling early this morning coupled with slightly higher dew points will lead to patchy fog through sunrise mainly in valleys, and also near agricultural fields aided by evapotranspiration. Otherwise, it's status quo in the short term in regards to the sensible weather with the near record ~600 dm ridge parked over the Upper Midwest supporting a continuation of the mainly clear skies, light winds and hot conditions through midweek. Not a lot of change thermally or moisture wise with the subsidence and light flow limiting advection. As a result, expect temperatures to lean on persistence plus 1-2 degrees daily with added solar energy and drying soils. This should result in highs mainly in the lower to mid 90s today and Wednesday, in line with progged 925 mb temps (23-25C) and NBM with probabilities of >90F at 95%. 50th percentile of NBM remains in the range of 92F-96F with some pockets of 96F+, however NBM has been a tad too warm based on recent verification and as such I have capped highs at 94/95F. Just a quick note the HRRR and RAP models should be used with extreme caution for temperatures as they continue to exhibit overmixing bias resulting in an overestimation of high temperatures and underestimation of surface dew points. With the limited advection and no source for a moisture boost expect any dew point increase to be through evapotranspiration. Tracking the dew points will remain critical to whether or not any heat headlines (advisory) may be needed. For now, will continue with subtle increase due to daily airmass modification which will support dew points mainly from the upper 60s to lower 70s. This along with the forecast highs in the lower to mid 90s will lead to heat index readings from the mid 90s to 100F. LREF and HREF probabilities for heat index readings greater than 100F are generally around 20-40%, thus speaking to the idea that while it can't be ruled out most likely this won't be widespread enough to warrant a heat headline. Of course, things can change if we get hotter than forecast or if dew points trend higher through a stronger ET component. Lows at night should bottom out in the upper 60s and lower 70s with ideal radiational cooling.

Bottom line, while this kind of heat is typical for July keep in mind the prolonged period of hot temperatures may pose a risk to those without adequate cooling, or those who must spend extended time outdoors. The light winds will limit evaporation of sweat and add to the discomfort. Thus, if you have to be outdoors for a long period of time make sure to take frequent breaks in the shade or A/C and drink plenty of water.

LONG TERM /THURSDAY THROUGH MONDAY/

Issued at 253 AM CDT Tue Jul 14 2026

Thursday begins the signal for some changes in the pattern. There is some signal and potential for a weak backdoor front off Lake Michigan settling down in/near our northern IL counties. In addition, a complex scenario unfolds with the heat dome breaking down into a couple of main centers, one out west and the other in the Mid Atlantic. There is an increasing signal for some upper level energy rotating around the backside of the Mid-Atlantic ridge and into the Mid-Mississippi Valley. This coupled with potentially a weak backdoor cool front will lead to some small chances (15-30%) for showers/storms Thursday afternoon and night. A bit more of an increase in moisture combined with highs in the 90s may bring about better potential for more areas to be around 100F for heat index readings Thursday afternoon. LREF though remains at 20% or less for the heat index >100F. Looking into this further the LREF mean 2m dew points increase to 70-75F widespread, but mean high temperatures are only in the lower 90s. It's possible that the increased moisture and spotty diurnal convection could foster more in the way of clouds, which will be something to monitor going forward. If we don't see much for any diurnal convection or clouds then I can see the potential for needing a heat advisory.

Overall, the ensembles and deterministic models support a further breaking down of the upper ridge late week and a amplification across the Intermountain West over the weekend. This strong monsoonal ridge will lead to strengthening NW flow across the Upper Midwest and Great Lakes. This points toward a more active pattern with the potential for periodic bouts of storms with ridge riders on the edge of the "ring of fire" pattern. This should also foster a return toward more normal temperatures, as highlighted by The Climate Prediction Center (CPC) in the recent 6-10 day/ 8-14 day temperature outlooks from July 19-27.

The NW flow aloft developing late week and through the weekend may also advect Canadian wildfire smoke into portions of the area, per latest RRFS vertical smoke forecasts and smoke forecast from the Canadian Wildland Fire Information System (CWFIS). Trajectories place our region more on the periphery at this time with the greater concentrations and impacts being suggested across MN/WI/MI, but something to keep an eye on.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 540 AM CDT Tue Jul 14 2026

Patchy river valley fog and changeable visibility from VLIFR to MVFR impacting KCID and potentially for a brief period at other sites will dissipate by 14z. Thereafter, VFR will dominate for much of the remainder of the period as a strong ridge of high pressure remains over the Midwest. This will lead to mainly clear skies, light winds, and hot conditions. More radiational valley fog is possible again late tonight (after 08z) and for now have introduced MVFR visibilities at KCID, KDBQ and KBRL where HREF probabilities for <5SM are 30-40%. Similar to this morning the potential is there for localized IFR to VLIFR visibility restrictions.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.